Some satellites comprise equipment that generates vibratory disruptions, which can be transmitted by the structure to payload elements sensitive to these disturbances. This is about isolating disruptive equipment by adequate devices that attenuate the vibrations they transmit to the load-bearing structure and/or isolating sensitive elements from the disturbances generated by using the same type of devices.
In the field of isolating equipment that generates disruptions or sensitive elements from vibrations, several types of solution are currently known.
A first family of solutions utilizes passive, i.e. inert, isolators usually taking the form of elastomer blocks, strips, springs, etc. Such devices are efficient in regards to high-frequency disturbances, but are inoperative on low-frequency disruptions, which may even be amplified in certain circumstances (in particular in frequency bands close to the resonance frequencies of the suspension).
Alternatively, it is known, in particular for expensive equipment that is highly sensitive to vibration, to implement active systems, i.e. devices comprising firstly a means of measuring the disruptions (forces or accelerations) induced by the vibrations within a target frequency bandand, secondly, means of generating corrective actions to defeat the induced disruptive effects. In this way, the transmitted vibrations are attenuated. However, these systems are only effective within a small frequency domain, characterized by the bandwidth of the active control.
In the case of an application more specific to equipment installed in a satellite, the state of the art as regards isolating disruptive equipment utilizes passive elements, active elements and systems combining an active element and a passive element mounted in parallel or in series.
For example, suspension devices are known in this field, which combine a low-stiffness passive element (spring, flexible strips) and an active element mounted in parallel, with the latter providing some damping thanks to a contactless actuator (e.g. “voice-coil” type).
Entirely passive isolation devices are also known, made of, for example, elastomer blocks (patents FR 2895052 and FR 2924191) and entirely active isolation devices made, for example, of a hexapod of active bars fitted with piezoelectric sensors and actuators mounted in series (publication: “Technology Predevelopment for active control of vibration and very high accuracy pointing systems”, A. Defendini and al, ESA's 4th Spacecraft Guidance, Navigation and Control Systems Conference, 1999).
According to the state of the art, these two isolator types may be combined by mounting in series a hexapod of active bars on a passive elastomer-based isolator. In such an assembly, the isolation functions are physically separated:                passive isolation is performed by elastomer blocks,        active control in series is realized by the active hexapod.        
At the hexapod, flexible mechanical hinge joints are positioned according to the state of the art at the extremity of each bar to provide the isostatic conditions required to eliminate all unwanted mechanical paths allowing vibrations to be transmitted in parallel.
One of the major difficulties inherent to this design comes from this requirement for isostatic conditions within the active lattice. The solutions retained conventionally utilize mechanical elements (strips, micromachined hinge joints, metal membranes, etc.); each one requires an antagonism to be resolved between the two following contradictory requirements:                realizing the lowest possible bending stiffness so as get close to isostatic conditions,        the resilience to tension-compression mechanical stresses so as to withstand the launch phase, which produces high stresses.        
It is well known that it is very difficult to realize flexible hinge joints designed to withstand the mechanical loads at launch.
This type of isolation device, which is both passive and active by superimposition of known elements, has certain limitations. Firstly, the device does not allow the different elements required for isolation to be incorporated optimally, because the isolation functions are physically separated. Secondly, it does not allow flexible hinge joints providing the required isostatic conditions to be manufactured easily.